Hatha yoga Prema Goet
This form of tapasya is a 18 year long process in which the yogi sits around the smoldering fire during the height of the summer for several hours. First the yogi starts with 5 piles of burning cow-dung for the first 3 years then it is increased by 7 piles after 3 years. 3 years after the first 6 years it is again increased by 12 piles of burning cow-dung, another 3 years later it is increased by 84 piles and then after another 3 years the yogi sits inside a full circle of fire. The final stage is after another 3 years in which the yogi sits inside of a full circle and a clay pot filled with burning cow-dung on the head. This completes the 18 year process which is then repeated again from the very beginning after its completion.